The Aggressive-class minesweepers are a class of US-built minesweepers. They are designated as MSO (Mine Sweeper Ocean), distinguishing them from the smaller coastal MSCs and inshore MSIs. Besides the US Navy, this class of vessels has also been used by the Belgian Navy and the Norwegian Navy, among others.

Background Minesweeping, or the disposal of naval mines, by these vessels is performed in different ways: Sweeping proper, with an underwater cable cutting the mooring cables of moored mines. The mines then come to the surface and are destroyed by gunfire. Acoustic sweeping, with a towed device producing noise to trigger acoustic mines. Magnetic sweeping, with a towed device producing a magnetic field to trigger magnetic mines. To protect the minesweeper itself against magnetic mines, the hull and superstructure of the ship are made of wood. Other components are made of non-magnetic materials, and any magnetic materials are strictly controlled.

Construction and disposition Of the 53 constructed for the United States Navy, 10 were built at Higgins Corp., New Orleans, Louisiana, 9 at J.M. Martinac Shipbuilding Corp., Tacoma, Washington, 8 at Wilmington Boat Works Inc., Wilmington, California, 6 at Luders Marine Construction Co. of Stamford, Connecticut, 4 at Broward Marine Inc, Fort Lauderdale, Florida, 4 at Martinolich Shipbuilding Co., San Diego, California, 3 at Burger Boat Company, Manitowoc, Wisconsin, 3 at Colberg Boat Works, Stockton, California, 2 at Fulton Shipyard, Antioch, California, 2 at Norfolk Naval Shipyard and 2 at Seattle Shipbuilding and Drydocking Co., Seattle, Washington.

33 of the class were decommissioned before the mid-1970s. Four ex-USN ships were sold to the Republic of China Navy 1994 and re-classed as s. was decommissioned 30 September 1994 in Tacoma, Washington and was the last Aggressive-class minesweeper in US Navy active service. On July 1st, 2025, the last Agile-class minesweeper, ROCS Yung Yang, the same minesweeper that was the last to retire from the US Navy, was officially decommissioned from Taiwan Navy service.

Units Ship NameHull no.BuilderCommission–DecommissionFateLink 422Luders Marine Construction Co. of Stamford, Connecticut1953–1971Sold for scrap 1980 423Luders Marine Construction Co. of Stamford, Connecticut1954-1970Destroyed by fire, sold for scrapping 1969 424Norfolk Naval Shipyard1953-1971Sold for scrap 1981 425Norfolk Naval Shipyard1953-1971Sold for scrap 1980426Fulton Shipyard, Antioch, California1954-1973Sold for scrap 1973 427Fulton Shipyard., Antioch, California1954-1992Sold for scrap 2001428 - 431 were US Dash-class minesweepers 432Colberg Boat Works., Stockton, California 1953-1971 Sold or loaned to Spain as Guadalete M41, 1971. 433Colberg Boat Works., Stockton, California 1953-1991 Scrapped 2002 434Colberg Boat Works., Stockton, California 1954-1972 Sold to be scrapped 1976, privately held until scrapped by USACE in 1993. 435J. M. Martinac Shipbuilding Corp., Tacoma, Washington 1954-1972 Sold for scrap 1973 436J. M. Martinac Shipbuilding Corp., Tacoma, Washington 1954-1972 Loaned to Philippines 1972Sold for scrap 1977 437Martinolich Shipbuilding Co., San Diego, California 1955-19701971-1991 Sold for scrap 2000 438Martinolich Shipbuilding Co., San Diego, California 1955-19701971-1991 Sold for scrap 2000 439Higgins Corp., New Orleans, Louisiana 1955-1992 Sold for scrap 2000 440Higgins Corp., New Orleans, Louisiana 1954-1993 Sold for scrap 2002 441Higgins Corp., New Orleans, Louisiana 1954-1993 Sold for scrap 2002 442Higgins Corp., New Orleans, Louisiana 1954-1990 Sold for scrap 1992 443Higgins Corp., New Orleans, Louisiana 1955-1989 Sold for scrap 1990 444J. M. Martinac Shipbuilding Corp., Tacoma, Washington 1954-1972 Loaned to Philippines 1972Scrapped 1977 445J. M. Martinac Shipbuilding Corp., Tacoma, Washington 1955-1973 Sunk after a fire 446Seattle Shipbuilding and Drydocking Co., Seattle, Washington 1954-1992 Scrapped 2002 447Seattle Shipbuilding and Drydocking Co., Seattle, Washington 1955-1972 Sold for scrap 1973 448Martinolich Shipbuilding Co., San Diego, California 1953-1990 Sold for scrap 1993 449Martinolich Shipbuilding Co., San Diego, California 1954-1991 Scrapped 2002 450 - 454 built at Bellingham Shipyards Co., Bellingham, Washington for France, not necessarily Aggressive-class ships. 455Wilmington Boat Works Inc., Wilmington, California 1954-1994 Sold to Taiwan 1994 and decommissioned in 2025. Scrapped in Kaohsiung, 2026. 456Wilmington Boat Works Inc., Wilmington, California 1954-1990 Sold for scrap 1992 457Wilmington Boat Works Inc., Wilmington, California 1954-1972 Sold for scrap 1973 458Higgins Corp., New Orleans, Louisiana 1955-1970 Sold for civilian use 1976Currently being restored by the Stockton Maritime Museum as a museum ship 459Higgins Corp., New Orleans, Louisiana 1955-1970 Sold for scrap 1981 460Higgins Corp., New Orleans, Louisiana 1955-1970 Sold for scrap 1971 461Higgins Corp., New Orleans, Louisiana 1955-1972 Sold for scrap 1979 462Higgins Corp., New Orleans, Louisiana 1955-1970 Sold for scrap 1978 463Wilmington Boat Works Inc., Wilmington, California 1954-1971 Initially loaned then sold to Spain as Guadalmedina M42, 1974. Decommissioned by Spain 2001. 464Wilmington Boat Works Inc., Wilmington, California 1954-1990 Sold for scrap 1992 465Wilmington Boat Works Inc., Wilmington, California 1954-1958 Grounded and sunk, 1958 in the Naruto Strait 466Wilmington Boat Works Inc., Wilmington, California 1954-1970 Sold for scrap 1976 467Wilmington Boat Works Inc., Wilmington, California 1954-1972 Sold for scrap 1976 468Luders Marine Construction Co. of Stamford, Connecticut 1954-1970 Sold for scrap 1971 469Luders Marine Construction Co. of Stamford, Connecticut 1955-1970 Grounded at Charleston Harbor then sold for scrap 1970. 470Luders Marine Construction Co. of Stamford, Connecticut 1955-1970 Sold for scrap 1971 471Luders Marine Construction Co. of Stamford, Connecticut 1950-1970 Sold for scrap 1979, scrapped 1983. 472Burger Boat Company, Manitowoc, Wisconsin 1954-1970 Sold for scrap 1971 473Burger Boat Company, Manitowoc, Wisconsin 1954-1972 Sold to Spain as Guadiana M44, 1972. Scrapped by Spain after 1999. 474Burger Boat Company, Manitowoc, Wisconsin 1955-1972 Sold for scrap 1979 475 - 487 built for France, Portugal, Spain, Belgium and the Netherlands, not necessarily Aggressive-class ships. 488J. M. Martinac Shipbuilding Corp., Tacoma, Washington 1955-19701971-1994 Sold to Taiwan 1994 and decommissioned in 2020. 489J. M. Martinac Shipbuilding Corp., Tacoma, Washington 1955-1994 Sold to Taiwan 1994 and decommissioned in 2013. 490J. M. Martinac Shipbuilding Corp., Tacoma, Washington 1955-19701971-1991/92 Sold for scrap 1994 491J. M. Martinac Shipbuilding Corp., Tacoma, Washington 1956-1971 Initially loaned in 1971 then sold to Spain as Guadalquivir M43 492J. M. Martinac Shipbuilding Corp., Tacoma, Washington 1956-1994 Sold to Taiwan 1994 and decommissioned 2021. 493Broward Marine Inc, Fort Lauderdale, Florida 1956-1966 Caught fire pier side at San Juan, Puerto Rico, sunk 1966. Later raised and sunk as an artificial reef. 494Broward Marine Inc, Fort Lauderdale, Florida 1957-1971 Sold for scrap 1978 495Broward Marine Inc, Fort Lauderdale, Florida 1957-1971 Sold for scrap 1978 496Broward Marine Inc, Fort Lauderdale, Florida1958-1971 Sold for scrap 1978 MSO-497497Cancelled, never built

See also HNLMS Onverschrokken (M886) - Dutch Aggressive-class minesweeper

References

External links

FAS - MSO-422 class GlobalSecurity - MSO-422 class ex MSO 483